The proposed research is an investigation of the maturation of vestibular function in man. Almost no systematic data are available on the maturation of vestibular function in the human child. In the proposed research, several parameters of vestibular nystagmus will be quantified in infants and children of different ages and in adults. These will include the slow phase amplitude and velocity, the fast phase amplitude and velocity, and the latency of nystagmus in response to various magnitudes of acceleration and deceleration. The per-acceleration and post-acceleration primary nystagmus and the secondary nystagmus parameters will be treated separately and compared with each other. These parameters of vestibular function will be compared to measures of oculomotor function which are neurophysiologically related to vestibular function. Altogether, these measures will provide a systematic approach to the investigation of the maturation of vestibular adaptation. They will be integrated, using statistical procedures developed in systems theory, into an empirically justified block diagram, or developmental series of block diagrams illustrating the quantitative interactions between subsystems of the vestibulo-ocular system including its peripheral and central components.